GRTM2CD 🗺️🐈🐕
GoodRelax Treasure Map to Cat and Dog
The Story
What if you found a treasure map?
You could ask a cat and a dog to each keep a piece.
When you need the map, just call them both.
I built a tool that does exactly that.
👉 Try it now
What It Does
This is a browser-only steganography tool.
It takes any file — PDF, ZIP,
whatever — and hides it across two ordinary PNG images.
You need both images to recover the file. Either one alone is useless.
How It Works
The process in one line:
Compress → Encrypt (AES-256-GCM) → Split across two images → Embed in LSBs → Fill remaining capacity with noise
The result:
- Each image looks like a normal PNG
- LSBs are indistinguishable from white noise
- Neither image alone reveals anything
- Both together reconstruct the original file perfectly
Why Two Images?
- Capacity — each image only needs to hold half the payload
- Deniability — no ciphertext continuity in either image
- Security — the AES key, IV, and ciphertext are all fragmented across both
One image found? Just a photo. Two images found? Still just two photos — unless you know what to look for.
Why Browser-Only?
No server means nothing can leak.
- No uploads, no installation, no build tools
- Works offline — just open the HTML file
- Cross-platform
Everything runs locally via Web Crypto API, Canvas API, and typed arrays.
Usage
Encode: Drop any file + two images → get two PNGs.
Decode: Drop the two PNGs → get the original file back. Order doesn't matter.
Tech Stack
- Vanilla JS (ES modules, no frameworks)
- Web Crypto API (AES-256-GCM)
- Canvas / OffscreenCanvas
- pako (zlib compression)
- PNG output only
No frameworks. No build tools. Single HTML + JS.
Try It Now
👉 https://goodrelax.github.io/gr-tools/grtm2cd/
Drop a file and two images — see what happens.
📂 https://github.com/GoodRelax/gr-tools
Please use responsibly.
Feedback and stars welcome♪ (c) 2026 GoodRelax
Top comments (0)